Dash and Alarm Electrical Problems

[zdorsch]

A friend of mine has a '97 Jetta (its the 2 liter, but I forget the model), which has developed a few electrical problems.

First when the car is turned off the tach will stay at around 1000 rpm and then upon restarting the guages will act like they have been reset; i.e. clock goes to 12:00 and the trip odometer and stereo resets.

Originally thought that it was the battery, so we tried switching with a battery that we know is good and nothing changed.

Secondly the alarm cannot be reset. We locked the door from the outside and set the alarm, but when reinserting the key in the outside lock the alarm will not disarm and of course goes off (not fun when you're poking around under the hood and not expecting to hear it!).

I found in the archives a note about the wiring in the door and will check that sometime soon. I will also try disarming the alarm from the passenger side.

A few other things that I noticed: the interior lights do not work when we hooked up the battery, but we were able to start the car without problems. The power windows will work, but the power locks will not. Not sure if this is related at all, but the sunroof will not work either. Once the car is started everything works as it should, speedometer registers the correct speed, tach operates normally, and the temp gauge operates.

With exception to the sunroof all of these electrical problems began last week after everything with the car had been normal.

Any ideas about these problems being related? Or any other parts to check?

Thanks

Zach

[veedubmechanic]

vacuum pump control module in trunk left side behind carpet. Controls alarm functions along with power locks. and i think also sunroof but not sure.

door latches are common failure.

[zdorsch]

After searching through the archives I found out how to disable the alarm. Last night I went over and we were going to disable the alarm. We had locked the car from the inside last time we worked on it so that we could leave the battery hooked up and move the jetta if we needed too.

As I was explaining what I had found my friend absent mindedly armed the alarm. I suggested that he try the passenger side--it didn't work either. But I did notice something about the lock and key: if we turned the key down to disarm the alarm and hold it in that position, the alarm light stops flashing. We were going to try this, but it was about 10 pm and his wife was still working on the getting the baby to sleep (needless to say didn't want to cause any problems there!).

Does this mean that its definitely the vacuum control module? More suggestions?

Thanks...